Adjustable piston expander



Jim. 31, 1939. F. E. MIILNER 2,145,426

ADJUSTABLE PISTON EXPEMIDER Filed Jan. 29, 1958 Q M WEMEZW@W Patented Jan. 31, 1939 TED STTES PATENT 9 Claims.

This invention relates to piston expanders used for expanding the skirt of a longitudinally split piston and particularly to an adjustable resilient expander.

Pistons have split skirts for the purpose of taking care of expansion. After a motor has been in use for a time, the piston becomes worn and distorted and slap develops. Loss of compression results and oil consumption is increased.

Various devices have been devised for the purpose of expanding the skirt of the piston under these circumstances, but it is a requirement of a piston expander that it shall be adjustable for every piston inasmuch as no two pistons have exactly the same characteristics of expansion and contraction nor will two pistons wear to exactly the same extent.

The general object of the present invention is to provide a piston expander that can be readily installed and have means of adjustment to take care of all the differences of expansion and contraction in individual pistons.

A further object is to provide a piston expander which will engage the piston skirt on each side of the slot at two points so that the skirt may be expanded either adjacent the head or adjacent the end of the piston skirt or both.

A still further object is to provide means for adjusting this skirt either adjacent the head or adjacent the end of the skirt and either uniormly or differentially.

Still another object is to provide a device of this character which is adaptable to many different sizes and types of pistons and to differences to wear.

Other objects will appear in the course of the following description.

lvly invention is illustrated in the accompanying drawing wherein:

Fig. l is a longitudinal sectional view through a piston and illustrating my expander applied to skirt of the piston, portions of the expander being in section.

. sig. 2 is a section on the line 2-2 of Fig. 1.

Fig. 3 is a fragmentary longitudinal section through one wall of the skirt showing an expander rod in elevation and illustrating the means whereby it is connected to the piston and skirt.

Fig. 4 is a section on the line ll-4 of Fig. 1.

Fig. 5 is a face view of the expander with the es disposed equi-distantly.

6 is a fragmentary sectional View through the collar showing the standing bars in elevation and illustrating notches on the bars for holding the collars and bars in adjusted position relative to each other.

Referring to this drawing, A designates a piston head having a skirt B which is longitudinally slotted at C. I do not wish, of course, to limit myself to the particular type of piston disclosed as the expander which I am about to describe is adaptabe to many different types of pistons having a split skirt.

My expander comprises two expanding bars EB and ii of steel wire. These bars are bowed towards each other and each bar at its upper end is formed with a coil l2, the extremity of the coil terminating in an outwardly extending portion it which is inserted into a drilled opening in the skirt of the piston, as shown in Fig. 3. After the extremity l3 has been inserted in this drilled opening, the outer end of this portion 53 is worked down by filing or otherwise so that it does not project, of course, in any way beyond the outer surface of the piston. The opposite ends of each of the expansion bars ll! is formed with an S-chaped coil to provide an eye M adapted to embrace a rivet it. The head of this rivet is set in a small countersink it formed in the skirt so that the head of the rivet Will not project outward beyond the outer surface of the skirt. As

efore remarked, the expanding bars H] are inwardly bowed towards each other and intermediate the ends of the expanding bars they are connected by means of a sliding ferrule or collar designated ll. Disposed above and below the ferrule or collar ii, that is, on each side of the ferrule or collar are the wedges 2i! and 2i. These wedges are both alike. The wedge 2! is formed with a longitudinally extending passage 22 which is unscrew-threaded. The wedge 20, however, is formed with a longitudinally extending passage 23 which is interiorly screw-threaded. Each of these wedges upon its outer face is formed with a groove 2 Extending loosely through the passage 22 is an adjusting screw 25 having a head 26 at one end and having its outer port remote from the head screw-threaded at 27. These threads 2? engage with the threads on the interior of the bore 23 but the screw passes loosely through the passage 22 and loosely through the passage defined by the collar ll. The head 25 bears against the adjacent end of the Wedge 2i as illustrated in Fig. 1.

With this construction it is possible to dispose the wedges 2i] and 2! each at the same distance from the ferrule or collar ll and dispose the ferrule or collar at the mlddles of the two expansion bars l0 and then by turning the screw 21 to force both of the wedges uniformly towards each other, thus causing an expansion of the outer ends of the expansion bars and the consequent uniform widening of the slot C in the piston skirt. On the other hand, it is possible, with this construction, to shift the screw through the collar or ferrule I'I, leaving this ferrule still at the middles of the expansion bars, thus causing the wedge 20 to engage the expansion bars nearer to the collar or ferrule I'l than the wedge 2|, then by rotating the screw the wedges are moved inward, but a greater expansion will be given to the ends of the expansion bars adjacent the head of the piston than to the ends of the expansion bars adjacent the end of the skirt. Vice versa, it is possible, of course, to adjust the screw 21 nearer to the head of the piston and thus cause the wedge 20 to be disposed at a greater distance from the collar or ferrule l1 than the wedge 2|, thus causing a greater expansion of the outer ends of the expansion bars than of the inner ends. It is also possible to shift the collar or ferrule I! along the expansion bars and then adjust the screw 25 and the wedges to any desired predetermined position so as to secure a proper adjustment of the expansion bars to in turn secure a differential adjustment of the slot C adjacent its opposite ends.

It will be understood, of course, that the expansion bars tend to contract the piston skirt by reason of their resilience or, in other words, if the wedges 2i] and 2! were omitted or were disposed as far as possible apart, the bars ill and H would tend to contract the piston skirt. The action of the wedges is to force these expansion bars it and H apart either uniformly or differentially and thus increase to any desired extent the width of the slot C. The grooves 24 in the wedges act to hold the expansion bars firmly in place and move the expansion bars accurately when the wedges are adjusted. The head 26 of the screw is nicked or otherwise formed for the application of a screw driver or other turning implement and is apertured at 28 for keying. The outwardly extending extremities It at the upper ends of the expansion bars Hi and H and the rivets I5 at the lower ends hold the expansion bars firmly in place and makes it impossible for them to come loose or get out of place.

This device can be installed very quickly and by its means either a uniform or non-uniform expansion or adjustment of the piston skirt may be readily made. This secures long life for the piston and a perfect fit. Furthermore, it will be seen that my expander does not merely engage at two points on opposite sides of the slot C but engages at four points, two points adjacent the head of the piston and two points adjacent the opposite end of the skirt so that uniform expansion or contraction can be secured, if desired. With my construction after my adjustable piston expander has been put in place, it can be adjusted without removing the expander from the piston because of the fact that the collar or ferrule I1 is adjustable along the expansion bars and that the wedges are adjustable. Thus either the wedges or the wedges and the collar I? may be adjusted longitudinally on the expansion bars so as to secure expansion exactly where it is needed. All expanders known to me only expand where they are attached to the piston, thus if they are attached adjacent the free end of the piston skirt, it will be this free end which will be expanded the most.

If they are attached adjacent the head of the piston, it will be the head of the piston where the force is applied and if the slot is expanded at this point, the slot in the end of the piston skirt will be expanded to a greater degree than is necessary. Inasmuch as the middle portion of my expanding bars cannot expand because of the collar, it follows that there may be differential adjustment both inward of this collar and outward of this collar at two separated points on the piston skirt.

Preferably, and in order to secure a positive interlock between the collar or ferrule ll and the expander bars 10 and H, the ferrule is formed as shown in Fig. 6, with opposed inwardly projecting teeth 29, and the bars l0 and H are formed with a plurality of notches 30, these notches being shown as five in number, thus providing a middle notch and several notches on each side of the middle. These notches are preferably about apart, but may be spaced at a less distance if desired. This provides a positive means for locking the bars Ill and H and the collar in relatively adjusted positions.

It will be noted that the upper ends of the bars l6 and H are coiled and then have the outwardly extending portions l3 engaging the wall of the piston whereas the lower ends of the expanding bars are formed with an S-shaped bend defining eyes by which the expanding bars are riveted to the wall of the piston. The reason for this difference is that it would be imposible to rivet the upper ends of these bars quickly to the piston skirt and it would not do to hook both the upper and lower ends to the piston skirt because of the danger of twisting up and coming unhooked. The coils i 2 help to brace the hook ends and cause the terminal ends I3 to stay in place. This spiral coil also gives flex ibility and resilience. The S-shaped coils or bends at the lower ends of the bars l9 and H give the necessary flexibility at these points and secures more flexibility at the lower ends of the bars than at the upper. This is for the reason that a split piston requires more flexibility at the lower end of an expander than at the upper end thereof. By riveting the lower ends of the bars H3 and H to the piston wall, it is assured that these ends will not come off as so often happens with other piston expanders now in use that only hook on the wall of the piston. By riveting these ends 14 to the piston, it will be impossible for the expander to twist and thus the rivets at the lower ends of the bars tend to hold the portions 53 at the upper ends of the bars firmly in place within the wall of the piston.

What is claimed is:

1- The combination with a piston having a longitudinally slotted skirt, of an expander comprising two longitudinally extending elements bowed inward towards each other, each element being connected to the skirt of the piston at both ends, the elements being disposed one on each side of the slot in the skirt, means connecting the elements intermediate their ends, wedges disposed between the elements and bearing against the same and located on each side of the connecting means, and means for simultaneously adlusting the said wedges toward or from said connecting means.

2. The combination with a piston having a longituclinally slotted skirt, of an expander comprising two longitudinally extending resilient elements bowed inward towards each other, each element being connected to the skirt of the piston at both ends, the elements being disposed on each side of the slot, the resilience of the elements tending to contract the skirt of the piston, and means whereby the elements may be forced apart at their opposite ends.

3. The combination with a piston having a longitudinally slotted skirt, of an expander comprising two longitudinally extending resilient elements bowed inward towards each other, each element being connected to the skirt of the piston at both ends, the elements being disposed on each side of the slot, the resilience of the elements tending to contract the skirt of, the piston, a collar connecting the elements intermediate their ends, wedges disposed between the elements and located on opposite sides of the collar, the wedges bearing against the elements, and a screw whereby said wedges may be drawn towards or forced away from each other.

4. The combination with a piston having a longitudinally slotted skirt, of an expander comprising two longitudinally extending resilient elements bowed inward towards each other, each element being connected to the skirt of the piston at both ends, the elements being disposed on each side of the slot, the resilience of the elements tending to contract the skirt of the piston, a collar connecting the elements intermediate their ends, wedges disposed between the elements and located on opposite sides of the collar, the collar having a passage through which the elements loosely pass, and a screw engaging the wedges and passing loosely through said collar.

5. The combination with a piston having a longitudinally slotted skirt, of an expander comprising two longitudinally extending resilient elements bowed inward towards each other, each element being connected to the skirt of the piston at both ends, the elements being disposed on each side of the slot, the resilience of the elements tending to contract the skirt of the piston, a collar connecting the elements intermediate their ends, wedges disposed between the elements and located on opposite sides of the collar, the collar having a passage through which the elements loosely pass, and a screw passing loosely through the collar having threads at one end engaging the innermost wedge and passing loosely through the outermost wedge but provided with aheadengaging against the outermost wedge.

6. The combination with a piston having a longitudinally slotted skirt, of an expander comprising two longitudinally extending resilient inwardly bowed elements, each of said elements at its end adjacent the head being formed with a coil and being engaged with the wall of the skirt, each of said elements at its outer end being coiled and rigidly engaged with the wall of the skirt, a collar having a passage through which said elements pass, wedges disposed on each side of the collar and engaging said elements, and a screw engaging said wedges and passing loosely through the collar.

7. A piston expander comprising two inwardly bowed resilient bars, each bar having means at its opposite ends whereby it may be rigidly connected to a piston skirt with the bars disposed on opposite sides of the slot of the skirt, a collar connecting said bars intermediate their ends, a screw passing loosely through the collar and wedges disposed one on each side of the collar and engaging between the inwardly bowed portions of the bars with which the screw engages.

8. A piston expander comprising two inwardly bowed resilient bars, each bar having means at its opposite ends whereby it may be rigidly connected to a piston skirt with the bars disposed on opposite sides of the slot of the skirt, a collar connecting said bars intermediate their ends, a screw passing loosely through the collar, and wedges disposed one on each side of the collar and engaging between the inwardly bowed portions of the bars with which the screw engages, the screw passing loosely through the outermost wedge but having screw-threaded engagement with the inner wedge.

9. A piston expander, including two inwardly bowed resilient bars adapted to be disposed one on each side of the slot of a piston skirt, each of said bars at its inner end being coiled and then extended outward to pass through a bore in the piston skirt, the opposite end of each bar being formed with an S-shaped coil constituting an eye adapted to be riveted to the piston skirt and a collar, the bars passing loosely through the collar, wedges disposed on each side of the collar and grooved on their edges to receive the bars, a screw passing loosely through the collar and having a head at one end and a screw-threaded portion at the opposite end, the screw having threaded engagement with the inner wedge but passing loosely through the outer wedge, the head of the screw bearing against said outer wedge, and means whereby said screw may be rotated and keyed.

FRED E. MILNER. 

